As is known in the art, there is an increasing trend to include radar systems in commercially available products. For example, it is desirable to include radar systems in automobiles, trucks boats, airplanes and other vehicle. Such radar systems must be compact and relatively low cost.
Furthermore, some applications have relatively difficult design parameters including restrictions on the physical size of the structure in addition to minimum operational performance requirements. Such competing design requirements (e.g. low cost, small size, high performance parameters) make the design of such radar systems relatively challenging. Among the design challenges is the challenge to provide an antenna system which meets the design goals of being low cost, compact and high performance.
In automotive radar systems, for example, cost and size considerations are of considerable importance. Furthermore, in order to meet the performance requirements of automotive radar applications, (e.g. coverage area) an array antenna is required. Some antenna elements which have been proposed for use in antenna arrays manufactured for automotive radar applications include patch antenna elements, printed dipole antenna elements and cavity backed patch antenna elements. Each of these antenna elements have one or more drawbacks when used in an automotive radar application.
For example, patch antenna elements and cavity backed patch antenna elements each require a relatively large amount of substrate area and thickness. Array antennas for automotive applications, however, have only a limited amount of area for reasons of compactness and cost. Printed dipole antennas can operate in a high density circuit environment, however, array antennas provided from printed dipole antenna elements give rise to “blind spots” in the antenna radiation pattern.
It would, therefore, be desirable to provide an antenna array that is compact which can operate in a high density circuit environment, and is relatively low cost to manufacture and yet provides an antenna array having relatively high performance characteristics.